Amazon EC2 - Amazon Web Services offers reliable, scalable, and inexpensive cloud computing services. Free to join, pay only for what you use.
Microsoft Azure - Windows Azure and SQL Azure enable you to build, host and scale applications in Microsoft datacenters.
Scaleway - Scaleway is the world's first Cloud Computing IaaS platform that offers ARM BareMetal SSD servers, starting at €0.006 on an hourly basis.
DigitalOcean - Simplifying cloud hosting. Deploy an SSD cloud server in 55 seconds.
MacStadium - MacStadium offer Mac colocation and dedicated server rentals plus VMware Mac Pro private cloud environments for large-scale iOS app
CloudSigma - CloudSigma is increasingly being recognized for its advancement of the cloud IaaS industry.